Monitoring a condition of a subject

A method for simultaneous measurement of heart rate and respiration rate of a subject, the method comprising:

• sensing motion of the subject and generating a sensed motion signal responsive to the sensed motion;
• determining a heartbeat-related signal from the sensed motion signal;
• determining a first breathing-rate-related signal from the heartbeat-related signal;
• determining a second breathing-rate-related signal directly from the sensed motion signal;
• and
• determining a validity of the heartbeat-related signal by comparing the first breathing-rate-related signal with the second breathing-rate-related signal.

A system for simultaneous measurement of heart rate and respiration rate of a subject, the system comprising:

• at least one motion sensor adapted to detect motion of the subject and generate a sensed motion signal responsive to the sensed motion;
• and
• a signal analyzer:
• adapted to determine a heartbeat-related signal from the sensed motion signal,
• adapted to determine a first breathing-rate-related signal from the heartbeat-related signal,
• adapted to determine a second breathing-rate-related signal directly from the sensed motion signal, and
• adapted to determine validity of the heartbeat-related signal by comparing the first breathing-rate-related signal with the second breathing-rate-related signal.